Many rolling bearings are assembled in an automobile transmission, however, many of those rolling bearings are operated in a state immersed in lubricant that is stored inside a transmission case. In this kind of lubricant, not only is there a possibility of the existence of foreign matter that has entered from the outside, but there is also a possibility that metallic abrasion powder that was generated in the engagement portion of the gears of the transmission is mixed therein as hard foreign matter. When this kind of hard foreign matter enters inside the rolling bearings and is bitten into the rolling contact portions between rolling surfaces and race surfaces of the rolling bearings, these rolling surfaces and race surfaces are scratched, and could become a cause of damage such as premature flaking or the like for the rolling bearing. In order to prevent this kind of damage, rolling bearings with seal rings are used as a rolling bearing in transmissions.
By using a seal ring having proper seal performance for a seal ring that is assembled in a rolling bearing with seal ring, lubricant is allowed to enter into the internal space of the rolling bearing where the rolling bodies are located, while at the same time, foreign matter that could cause damage to the rolling bearing is prevented from entering into this internal space.
As construction of a rolling bearing with seal ring that can be used for this kind of use, there is construction such as disclosed in German Utility Model No. 20,306,004, and International Publication No. WO 2011/051045. FIG. 9 illustrates the construction of the rolling bearing 1 with seal ring that is disclosed in German Utility Model No. 20,306,004. The rolling bearing 1 with seal ring comprises an outer ring 2 and inner ring 3 that are concentrically located with each other, a plurality of balls 4, each of which is a rolling body, a seal ring 5 that is located on one end side in the axial direction, and a shield ring 6 that is located on the other end side in the axial direction. The balls 4 are held in a cage 7 and arranged between an outer ring raceway 8 that is provided around the inner-circumferential surface of the outer ring 2, and an inner ring raceway 9 that is provided around the outer-circumferential surface of the inner ring 3 so as to be able to roll freely.
The contact seal ring 5 is composed of an elastic member 18 that is made using an elastomer such as rubber that is reinforced with a circular ring-shaped metal core 10 that is made of metal plate, and this seal ring 5 is such that an elastic fastening portion 11 is formed around the outer-circumferential edge portion and a seal lip 12 is formed around the inner-circumferential edge portion, with each protruding in the radial direction from the peripheral edge portions of the metal core 10. With the elastic fastening portion 11 of the seal ring 5 locked into a fastening groove 13a that is formed around the inner-circumferential surface of one end portion (left side in FIG. 9) of the outer ring 2, the tip-end edge of the seal lip 12 of the seal ring 5 comes in sliding contact all the way around a stepped surface 14a that is provided on the outer-circumferential surface of one end portion of the inner ring 3. Moreover, the non-contact shield ring 6 is formed entirely into a circular ring shape by bending metal plate. With the outer-circumferential edge portion of the shield ring 6 fastened to a fastening groove 13b that is formed around the inner-circumferential surface of the other end portion (right side in FIG. 9) of the outer ring 2, the inner-circumferential edge of the shield ring 6 comes close to and faces around the entire circumference a stepped surface 14b that is provided around the outer-circumferential surface of the other end portion of the inner ring 3. In this kind of rolling bearing 1 with seal ring, by properly regulating the location of the seal ring 5 and shield ring 6 such that, for example, the seal ring 5 is located on the side where foreign matter exists, and the shield ring 6 is located on the side where there is a low possibility that foreign matter will enter in, an effect of preventing foreign matter from entering inside, and an effect of delaying the time until serious damage occurs are obtained. It is not illustrated in the figures, however, construction is also conventionally known in which the outer-circumferential surface of the end portion of the inner ring that is separated from the inner ring raceway is a simple cylindrical surface, and the inner-circumferential edge of the seal lip comes in sliding contact with this cylindrical surface.
As illustrated in FIG. 9, when this kind of rolling bearing 1 with seal ring is assembled in rotation support portions of an automobile transmission, the inner ring 3 is fitted around the outside of a shaft 15, and a stopper ring 17 that is fastened to a fastening groove 16 that is formed around the outer-circumferential surface of the shaft 15 can be used to position the inner ring 3 in the axial direction with respect to the shaft 15. In the case of this kind of construction, the installation space of the rolling bearing 1 with respect to seal ring on the shaft 15 side increases by the amount of the thickness of the stopper ring 17, which is a disadvantage from the aspect of being able to make the automobile transmission more compact and lightweight.